Cylindrical Body Fitting Structure and Inverter

The present invention relates to a cylindrical body fitting structure and an inverter.

In power converters, the water passage pipe and the housing are subjected to pressing and fitting between members made of an aluminum material, which requires a fitting structure for which a concern that an airtight defect or a process defect occurs is considered. For example, PTL 1 below discloses that a cooling structure ensures high reliability by taking measures against leakage of the coolant while maintaining miniaturization and weight reduction when the fitted members are made of different materials, an adhesive is used on the press fitting surfaces, and a press fitting jig and a galling prevention jig are used.

PTL 1: JP 2021-118616 A

In the conventional structures, although the pressing and fitting between members made of the same material ensures airtightness without using an anaerobic adhesive agent at the fitting portion, the press fitting between aluminum materials has caused a concern that the press fitting portions may bite or gall with each other, resulting in an airtight defect or a process defect. In view of this, an object of the present invention is to provide a cylindrical body fitting structure and an inverter that successfully suppress galling during pressing and fitting and reduce airtight defects.

The cylindrical body fitting structure and the inverter according to the present invention include: a first cylindrical body having a first cylindrical fitting portion that is fitted with another cylindrical body; and a second cylindrical body having a second cylindrical fitting portion that is fitted with the first cylindrical fitting portion, the first cylindrical body and the second cylindrical body being fitted and connected with each other, wherein at least one of the first cylindrical fitting portion and the second cylindrical fitting portion is provided with a press fitting load release portion that is bent in a radial direction when the first cylindrical fitting portion and the second cylindrical fitting portion are fitted with each other.

According to the present invention, it is possible to provide a cylindrical body fitting structure and an inverter that successfully suppress galling during pressing and fitting and reduce airtight defects.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following description and drawings are examples for describing the present invention, and are omitted and simplified as appropriate for the sake of clarity of description. The present invention can be carried out in various other forms. Unless otherwise specified, each component may be singular or plural.

The position, size, shape, range, and the like of each component illustrated in the drawings do not necessarily represent the actual position, size, shape, range, and the like in order to facilitate understanding of the invention. Therefore, the present invention is not necessarily limited to the position, size, shape, range, and the like disclosed in the drawings.

1 2 5 2 7 5 3 3 5 3 5 A power converterincludes a caseand a lower cover. The casehouses a power modulehaving a switching semiconductor element to perform power conversion. The lower coverhas a water passage pipe. The water passage pipeis press-fitted and connected to the lower cover. The water passage pipeand the lower coverare the same metal member formed by aluminum die-casting.

2 5 4 2 5 5 4 2 5 3 5 2 3 1 7 In the portion where a cooling flow path is formed between the caseand the lower cover, a sealantis applied to the groove of the connection portion between the caseand the lower cover. The lower coveris attached to sandwich the sealant, and is fixed with a bolt, so that the cooling flow path that is formed between the caseand the lower coveris sealed. In this way, the entire flow path of the water passage pipeattached to the lower coverbecomes a closed space. Therefore, a cooling flow path to connect the caseand the water passage pipeis formed, and the refrigerant flowing through the inside thereof cools the entire power converterincluding the power module.

7 2 6 2 7 1 2 2 7 The power moduleis inserted into the case. A power module plateis assembled to the caseto hold the inserted power module. The power converteris provided with a flow path communicating with a cylindrical body, and housed in the case. Inside the flow path formed in the case, a refrigerant flows to cool the power module.

2 a FIG.() 2 b FIG.() 2 c FIG.() 3 3 2 3 11 2 2 3 15 3 16 is an internal structural view of the water passage pipe;is a view illustrating a state in which the water passage pipeis fitted to the case; andis a view illustrating a state of the fitting surface. The water passage pipeis applied with a lubricating oil (not illustrated) on a press fitting surfaceto fit with the case, for the purpose of preventing damage during press fitting. Hereinafter, description will be made such that the fitting portion of the casewith the water passage pipeis referred to as a first cylindrical body, and the water passage pipeis referred to as a second cylindrical body.

16 9 10 16 15 9 16 10 15 9 11 16 15 11 11 The second cylindrical bodyhas a surface-pressing portionthat is a plane perpendicular to a press fitting directionof the second cylindrical bodyto the first cylindrical body. When the surface-pressing portionis pressed with a press fitting jig (not illustrated), the second cylindrical bodymoves in the press fitting directionto be fitted with the first cylindrical body. Further, press fitting through the surface-pressing portioncan suppress a partial contact between the press fitting surfaceof the second cylindrical bodyand the first cylindrical body. As described above, the press fitting load can be uniformly distributed. Therefore, it is possible to prevent the occurrence of inclination during pressing and fitting and to contribute to suppressing the galling of the press fitting surfaceand preventing damage of the press fitting surface.

16 12 16 16 15 12 At the tip of the second cylindrical body, a guide surfacehaving a straight shape is provided. In this manner, the second cylindrical bodyhas an aligning structure to align the centers of the holes of the fitted second cylindrical bodyand first cylindrical bodyat the beginning of the press fitting step. In addition, since the guide surfaceis provided, the cores of the cylindrical fitting portions can be aligned during press fitting to suppress a partial contact of the press fitting surface and uniformly distribute the fitting load, thereby the effect of suppressing damage and galling of the press fitting surface can be obtained.

2 b FIG.() 16 15 12 11 16 15 11 11 16 15 16 15 15 a a As shown in, as the second cylindrical bodyis gradually press-fitted while being contacted with the first cylindrical body, the contact surface is switched from the guide surfaceto the press fitting surface. In this manner, when the second cylindrical bodyis press-fitted into the first cylindrical body, the portion of the first contact therebetween is a press fitting start portion. That is, the press fitting start portionis the intersection of the guide range and the press fitting range. The press fitting range means a range where the axial diameter of the second cylindrical bodyis larger than the hole diameter of the first cylindrical body. The tip of the second cylindrical bodypartially expands the inner diameter of the first cylindrical bodyas being press-fitted into the first cylindrical body.

12 During press fitting, the portion to which the highest stress is applied is the switching portion from the guide surfaceto the press fitting, the switching portion serving as a starting point of galling. Galling is less likely to occur in the middle of press fitting, and galling usually occurs from the switching point. Therefore, according to the configuration of the present invention, a portion to release the press fitting load is provided to temporarily increase the diameter reduction, thereby successfully decreasing the galling potential.

16 11 11 16 15 16 15 a a The second cylindrical bodycan be deformed such that the tip is bent radially inward based on a fulcrum formed at a position on the back side (the upper side in the drawing) of the press fitting start portion, so that the local stress at the press fitting start portioncan be alleviated. The term “bend” as used herein is as follows: the outer shape of the second cylindrical bodyis larger than the inner diameter of the first cylindrical body, and therefore, the press fitting dimension is balanced through the diameter reduction of the second cylindrical bodyand the diameter increase of the first cylindrical bodyduring press fitting, and thereby a large dimension change occurs from the diameter reduction or the diameter increase. Details of the portion related to the bend will be described later.

15 15 16 16 16 15 16 15 16 18 1 a a a a a The first cylindrical bodyhas a first cylindrical fitting portionthat is fitted with the second cylindrical body(or another cylindrical body). The second cylindrical bodyhas a second cylindrical fitting portionthat is fitted with the first cylindrical fitting portion. As described above, the second cylindrical fitting portionis press-fitted into the first cylindrical fitting portionso that the second cylindrical bodyis connected to the flow path. In this manner, the cylindrical body fitting structure obtained by fitting and connecting therebetween allows a refrigerant to flow through the entire power converter.

16 19 15 16 a a a In such a fitting structure, the second cylindrical fitting portionis provided with a press fitting load release portionthat is bent in a radial direction when the first cylindrical fitting portionand the second cylindrical fitting portionare fitted with each other.

19 15 16 15 16 19 11 15 16 11 15 14 15 16 a a a a a a a a a a a The press fitting load release portionis provided at an end portion of the first cylindrical fitting portionor an end portion of the second cylindrical fitting portion, which face with each other, in a portion where the first cylindrical fitting portionand the second cylindrical fitting portionare fitted with each other. Further, as described above, the press fitting load release portionhas a press fitting start portionthat is first press-fitted and contacted at a surface where the first cylindrical fitting portionand the second cylindrical fitting portionare fitted and contacted with each other. The press fitting start portionfirst comes into contact with a minimum inner diameter portion in an inner circumference surface of the first cylindrical fitting portionat an outer circumference portion of the first thinned portionas described later when the first cylindrical fitting portionand the second cylindrical fitting portionare press-fitted and contacted with each other.

19 13 15 16 15 16 13 14 11 16 15 16 16 a a a a a a a a The press fitting load release portionhas a bend fulcrum portionserving as a fulcrum for bending the first cylindrical fitting portionor the second cylindrical fitting portionin the radial direction when the first cylindrical fitting portionand the second cylindrical fitting portionare fitted with each other. The bend fulcrum portionis determined by providing the first thinned portionas described later, and is positioned and provided on the reverse side of the press fitting direction side of the press fitting start portionwhen seen from the second cylindrical body. This allows deformation when the first cylindrical fitting portionand the second cylindrical fitting portionare pressed and fitted with each other, and the end portion of the second cylindrical fitting portionis bent radially inward, thereby obtaining an effect of alleviating the stress during fitting. In addition, management in the mass production process becomes easy, and this also contributes to improving yield in terms of defective press fitting.

19 14 16 15 16 3 16 14 a a a The press fitting load release portionhas a first thinned portionon a side of the second cylindrical fitting portionin a portion where the first cylindrical fitting portionand the second cylindrical fitting portionare fitted with each other. The entire thickness of the water passage pipeincluding the second cylindrical bodyis a thickness necessary for molding by die casting. However, the first thinned portionin the vicinity of the tip of the press fitting portion is formed to be thinner than the standard thickness. Such a configuration can contribute to stabilizing and ensuring the airtight performance without damage on the press fitting surface, and improving the yield. In addition, after completion of the press fitting, the airtightness does not change because the press fitting length is equal after press fitting, which contributes to improved reliability.

15 16 15 162 As described above, the first cylindrical bodyand the second cylindrical bodyare formed of the same material. As a result, there is no linear expansion difference when the members are thermally affected, and the state of the press fitting surfaces can be made constant when the members are connected to each other, so that reliability can be improved. In addition, since the first cylindrical bodyand the second cylindrical bodyare made of the same material, the press fitting surfaces do not separate from each other due to temperature change, so that the airtightness is not affected. In addition, it is not necessary to use an anaerobic adhesive agent, which causes a risk of airtight defects due to deterioration over time when used at the press fitting surface, and high durability performance is obtained. In addition, this can also contribute to supporting clients who wish to use no adhesive agent in water path portions.

13 14 14 The bend fulcrum portionis formed at the R-end portion of the first thinned portion. The thinned region of the first thinned portionis not limited, and is formed such that the thinned region is bent in response to a press fitting load determined from the necessary airtight characteristics. In this way, it is possible to alleviate the local stress at the press fitting start point and to prevent the surface from being damaged or curled.

14 12 16 11 12 16 12 16 a The first thinned portionhas the guide surfacedescribed above on a press fitting side of the second cylindrical body, as compared with the press fitting start portion, in an outer circumference surface. The guide surfacehas a cylindrical surface parallel to a press fitting direction of the second cylindrical body. In this manner, since the range of the guide surfaceat the tip of the second cylindrical bodyhas a straight shape, the length of the guide, which is a surface to first come into contact therewith during press fitting, can be widely formed, so that the centering accuracy is improved during press fitting.

19 16 16 21 22 21 21 22 a As the press fitting load release portion, the end portion of the second cylindrical bodyis cut out from an insertion tip portion of the second cylindrical fitting portiontoward a reverse side of an insertion direction; and has at least three cut-out portionsarranged at equal intervals in a circumferential direction of the end portion, and at least three peripheral wall portionsadjacent to each other in the circumferential direction between the cut-out portions. Note that the cut-out portionand the peripheral wall portionare illustrated one by one for the convenience of the cross-sectional view of the drawing.

11 15 21 15 16 a a a a The press fitting start portionfirst comes into contact with a minimum inner diameter portion in an inner circumference surface of the first cylindrical fitting portionat an outer circumference portion of the cut-out portionswhen the first cylindrical fitting portionand the second cylindrical fitting portionare press-fitted and contacted with each other.

13 16 11 21 16 15 16 a a a The bend fulcrum portionis formed on a reverse side of a press fitting side of the second cylindrical body, as compared with the press fitting start portion, in an inner circumference portion of the cut-out portions; and supports a radially inward bend of the second cylindrical bodywhen the first cylindrical fitting portionand the second cylindrical fitting portionare contacted with each other.

16 21 13 11 21 b a In order to bend the second cylindrical body, a cut-out apex(bend fulcrum portion) needs to be provided on the back side of the press fitting start portionin the press fitting direction. Note that the cut-out shape of the cut-out portionis not limited.

4 FIG. 21 16 15 21 22 21 12 Accordingly, similarly to the embodiment described with reference to, the radially inward diameter reduction of the cut-out portioncan alleviate stress concentration when the second cylindrical bodyis press-fitted into the first cylindrical body. In addition, since the surface pressure after press fitting is substantially unchanged, there is an advantage that there is no adverse effect on airtightness. In addition, when three or more cut-out portionsare provided, the deformation in the circumferential direction is hardly biased as compared with the case when two or less cut-outs are provided, so that the peripheral wall portionsare evenly deformed as a whole. In addition, the cut-out portionis advantageous in that there is no need to reduce the thickness of the guide surface.

19 20 15 16 11 16 20 15 16 a a a a a a The press fitting load release portionhas a second thinned portionon a side of the first cylindrical fitting portion in a portion where the first cylindrical fitting portionand the second cylindrical fitting portionare fitted with each other. The press fitting start portionfirst comes into contact with a maximum outer diameter portion in an outer circumference surface of the second cylindrical fitting portionat an inner circumference portion of the second thinned portionwhen the first cylindrical fitting portionand the second cylindrical fitting portionare press-fitted and contacted with each other.

13 16 11 20 15 15 16 a, a a The bend fulcrum portionis formed on a reverse side of a press fitting side of the second cylindrical body, as compared with the press fitting start portionin an outer circumference portion of the second thinned portion; and supports a radially outward bend of the first cylindrical bodywhen the first cylindrical fitting portionand the second cylindrical fitting portionare contacted with each other.

20 15 19 11 13 11 15 a a As described above, when a groove is formed to provide the second thinned portionradially outward at the end portion of the side of the first cylindrical bodyas the press fitting load release portion, and the depth of the groove is slightly deeper than that of the press fitting start portion, the bend fulcrum portionis provided on the press fitting direction side of the press fitting start portion. As a result, the diameter increase of the first cylindrical bodycan alleviate stress concentration during press fitting; and there is no influence of airtightness since the surface pressure after press fitting is substantially unchanged.

19 14 16 15 16 11 15 14 15 16 a a a a a a a The press fitting load release portionhas a first thinned portionon the outer circumference side of the second cylindrical fitting portionin a portion where the first cylindrical fitting portionand the second cylindrical fitting portionare fitted with each other. The press fitting start portionfirst comes into contact with a maximum outer diameter portion in an outer circumference surface of the first cylindrical fitting portionat an inner circumference portion of the first thinned portionwhen the first cylindrical fitting portionand the second cylindrical fitting portionare press-fitted and contacted with each other.

13 16 11 14 16 15 16 15 16 a a a The bend fulcrum portionis formed on a reverse side of a press fitting side of the second cylindrical body, as compared with the press fitting start portion, in an outer circumference portion of the first thinned portion; and supports a radially outward bend of the second cylindrical bodywhen the first cylindrical fitting portionand the second cylindrical fitting portionare contacted with each other. In this manner, in the case of a structure in which the outer shape of the first cylindrical bodyis fitted to the inner diameter side of the second cylindrical body, it is possible to constantly secure the flow path cross-sectional area and alleviate the stress during press fitting.

19 20 15 15 16 11 16 20 15 16 13 16 11 20 15 15 16 a a a a a a a a a a The press fitting load release portionhas a second thinned portionon a side of the first cylindrical fitting portionin a portion where the first cylindrical fitting portionand the second cylindrical fitting portionare fitted with each other. The press fitting start portionfirst comes into contact with a minimum inner diameter portion in an inner circumference surface of the second cylindrical fitting portionat an outer circumference portion of the second thinned portionwhen the first cylindrical fitting portionand the second cylindrical fitting portionare press-fitted and contacted with each other. The bend fulcrum portionis formed on a press fitting side of the second cylindrical body, as compared with the press fitting start portion, in an inner circumference portion of the second thinned portion; and supports a radially inward bent of the first cylindrical bodywhen the first cylindrical fitting portionand the second cylindrical fitting portionare contacted with each other.

15 16 7 FIG. Thereby, in the case of a structure in which the outer shape of the first cylindrical bodyis fitted to the inner diameter side of the second cylindrical body, it is possible to constantly secure the flow path cross-sectional area and alleviate the stress during press fitting, as described in.

13 15 16 19 15 16 Although the configuration of the present invention has been described above, the bend fulcrum portionmay be provided on both the first cylindrical bodyside and the second cylindrical bodyside. When the press fitting load release portionis provided on both the first cylindrical bodyand the second cylindrical bodyby combining both the configurations as described above, not only the local stress during press fitting is load-released by bending, but also the deformation can be made with a small load so that the operational effects as described above are further improved.

15 15 16 16 15 15 16 15 16 19 15 16 a a a a a a a (1) The cylindrical body fitting structure according to the present invention includes: a first cylindrical bodyhaving a first cylindrical fitting portionthat is fitted with another cylindrical body; and a second cylindrical bodyhaving a second cylindrical fitting portionthat is fitted with the first cylindrical fitting portion, the first cylindrical bodyand the second cylindrical bodybeing fitted and connected with each other. At least one of the first cylindrical fitting portionand the second cylindrical fitting portionis provided with a press fitting load release portionthat is bent in a radial direction when the first cylindrical fitting portionand the second cylindrical fitting portionare fitted with each other. Thereby, it is possible to provide a cylindrical body fitting structure that successfully suppresses galling during pressing and fitting and reduces airtight defects. 15 16 19 14 20 15 16 14 20 13 a a a a (2) In at least one of the first cylindrical fitting portionand the second cylindrical fitting portion, the press fitting load release portionhas a thinned portionorthat is bent in the radial direction when the first cylindrical fitting portionand the second cylindrical fitting portionare fitted with each other. The thinned portionsandinclude a bend fulcrum portionserving as a fulcrum for bending in the radial direction. Thereby, the press fitting load can be uniformly distributed. Therefore, it is possible to prevent the occurrence of inclination during pressing and fitting. 19 15 16 15 16 11 15 16 13 10 11 15 10 11 16 15 166 15 16 11 11 a a a a a a a a a a a a a (3) The press fitting load release portionis provided at an end portion of the first cylindrical fitting portionor an end portion of the second cylindrical fitting portion, which face with each other, in a portion where the first cylindrical fitting portionand the second cylindrical fitting portionare fitted with each other; and has a press fitting start portionthat is first press-fitted and contacted at a surface where the first cylindrical fitting portionand the second cylindrical fitting portionare fitted and contacted with each other. The bend fulcrum portionis positioned on a press fitting directionside of the press fitting start portionwhen seen from the first cylindrical body, and is positioned on a reverse side of the press fitting directionside of the press fitting start portionwhen seen from the second cylindrical body; and an end portion of the first cylindrical fitting portionis bent radially outward, and an end portion of the second cylindrical fitting portionis bent radially inward when the first cylindrical fitting portionand the second cylindrical fitting portionare fitted with each other. This contributes to suppressing the galling of the press fitting surfaceand to preventing damage of the press fitting surface. 19 14 16 15 16 11 15 14 15 16 13 16 11 14 16 15 16 16 a a a a a a a a a a (4) The press fitting load release portionhas a first thinned portionon a side of the second cylindrical fitting portionin a portion where the first cylindrical fitting portionand the second cylindrical fitting portionare fitted with each other. The press fitting start portionfirst comes into contact with a minimum inner diameter portion in an inner circumference surface of the first cylindrical fitting portionat an outer circumference portion of the first thinned portionwhen the first cylindrical fitting portionand the second cylindrical fitting portionare press-fitted and contacted with each other. The bend fulcrum portionis formed on a reverse side of a press fitting side of the second cylindrical body, as compared with the press fitting start portion, in an inner circumference portion of the first thinned portion; and supports a radially inward bend of the second cylindrical bodywhen the first cylindrical fitting portionand the second cylindrical fitting portionare contacted with each other. In this manner, the second cylindrical bodyon the press fitting side mainly obtains the effect of alleviating stress during fitting. 16 16 21 22 21 11 15 21 15 16 13 16 11 21 16 15 16 16 a a a a a a a a (5) The end portion of the second cylindrical bodyis cut out from an insertion tip portion of the second cylindrical fitting portiontoward a reverse side of an insertion direction; and has at least three cut-out portionsarranged at equal intervals in a circumferential direction of the end portion, and at least three peripheral wall portionsadjacent to each other in the circumferential direction between the cut-out portions. The press fitting start portionfirst comes into contact with a minimum inner diameter portion in an inner circumference surface of the first cylindrical fitting portionat an outer circumference portion of the cut-out portionswhen the first cylindrical fitting portionand the second cylindrical fitting portionare press-fitted and contacted with each other. The bend fulcrum portionis formed on a reverse side of a press fitting side of the second cylindrical body, as compared with the press fitting start portion, in an inner circumference portion of the cut-out portions; and supports a radially inward bend of the second cylindrical bodywhen the first cylindrical fitting portionand the second cylindrical fitting portionare contacted with each other. In this manner, the second cylindrical bodyon the press fitting side, even having an end portion in another embodiment, mainly obtains the effect of alleviating stress during fitting. 19 20 15 15 16 11 16 20 15 16 13 16 11 20 15 15 16 15 a a a a a a a a a a (6) The press fitting load release portionhas a second thinned portionon a side of the first cylindrical fitting portionin a portion where the first cylindrical fitting portionand the second cylindrical fitting portionare fitted with each other. The press fitting start portionfirst comes into contact with a maximum outer diameter portion in an outer circumference surface of the second cylindrical fitting portionat an inner circumference portion of the second thinned portionwhen the first cylindrical fitting portionand the second cylindrical fitting portionare press-fitted and contacted with each other. The bend fulcrum portionis formed on a reverse side of a press fitting side of the second cylindrical body, as compared with the press fitting start portion, in an outer circumference portion of the second thinned portion; and supports a radially outward bend of the first cylindrical bodywhen the first cylindrical fitting portionand the second cylindrical fitting portionare contacted with each other. In this manner, the first cylindrical bodyon the press-fitted side mainly obtains the effect of alleviating stress during fitting. 19 14 16 15 16 11 15 14 15 16 13 16 11 14 16 15 16 16 15 16 a a a a a a a a a a (7) The press fitting load release portionhas a first thinned portionon a side of the second cylindrical fitting portionin a portion where the first cylindrical fitting portionand the second cylindrical fitting portionare fitted with each other. The press fitting start portionfirst comes into contact with a maximum outer diameter portion in an outer circumference surface of the first cylindrical fitting portionat an inner circumference portion of the first thinned portionwhen the first cylindrical fitting portionand the second cylindrical fitting portionare press-fitted and contacted with each other. The bend fulcrum portionis formed on a reverse side of a press fitting side of the second cylindrical body, as compared with the press fitting start portion, in an outer circumference portion of the first thinned portion; and supports a radially outward bend of the second cylindrical bodywhen the first cylindrical fitting portionand the second cylindrical fitting portionare contacted with each other. In this manner, even when the second cylindrical bodyis fitted into a convex cylindrical body as the first cylindrical body, the second cylindrical bodyon the press fitting side mainly obtains the effect of alleviating stress during fitting. 19 20 15 15 16 11 16 20 15 16 13 16 11 20 15 15 16 16 15 15 a a a a a a a a a a (8) The press fitting load release portionhas a second thinned portionon a side of the first cylindrical fitting portionin a portion where the first cylindrical fitting portionand the second cylindrical fitting portionare fitted with each other. The press fitting start portionfirst comes into contact with a minimum inner diameter portion in an inner circumference surface of the second cylindrical fitting portionat an outer circumference portion of the second thinned portionwhen the first cylindrical fitting portionand the second cylindrical fitting portionare press-fitted and contacted with each other. The bend fulcrum portionis formed on a press fitting side of the second cylindrical body, as compared with the press fitting start portion, in an inner circumference portion of the second thinned portion; and supports a radially inward bent of the first cylindrical bodywhen the first cylindrical fitting portionand the second cylindrical fitting portionare contacted with each other. In this manner, even when the second cylindrical bodyis fitted into a convex cylindrical body as the first cylindrical body, the first cylindrical bodyon the press-fitted side mainly obtains the effect of alleviating stress during fitting. 14 12 16 11 12 16 a (9) The first thinned portionhas a guide surfaceon a press fitting side of the second cylindrical body, as compared with the press fitting start portion, in an outer circumference surface; and the guide surfacehas a cylindrical surface parallel to a press fitting direction of the second cylindrical body. Thereby, the centering accuracy is improved during press fitting. 15 16 (10) The first cylindrical bodyand the second cylindrical bodyare made of a same material. Thereby, connection reliability is improved. 16 9 16 (11) The second cylindrical bodyhas a surface-pressing portionthat is a plane perpendicular to a press fitting direction of the second cylindrical body. Thereby, partial contact during press fitting can be suppressed. 1 2 18 15 16 7 2 18 7 1 (12) A power converterincludes: a housinghaving a flow pathcommunicating with the first cylindrical bodyand the second cylindrical body; and a power modulethat is housed in the housingand has a switching semiconductor element to perform power conversion. Inside the flow path, a refrigerant flows to cool the power module. Thereby, it is possible to provide a power converterhaving a cylindrical body fitting structure that successfully suppresses galling during pressing and fitting and reduces airtight defects. According to the embodiments of the present invention described above, the following operational effects are obtained.

Note that the present invention is not limited to the above embodiments, and various modifications and other configurations can be combined without departing from the gist of the present invention. In addition, the present invention is not limited to one including all the configurations described in the above embodiments, and includes one in which a part of the configurations is deleted.

1 power converter 2 case 3 water passage pipe 4 sealant 5 lower cover 6 power module plate 7 power module 9 surface-pressing portion 10 press fitting direction 11 press fitting surface 11 a press fitting start portion 12 guide surface 13 bend fulcrum portion 14 first thinned portion 15 first cylindrical body 15 a first cylindrical fitting portion 16 second cylindrical body 16 a second cylindrical fitting portion 18 flow path 19 press fitting load release portion 20 second thinned portion 21 cut-out portion 21 b cut-out apex 22 peripheral wall portion 23 cylindrical surface